class_docstr: Base class for WK3l datasets (WK3l-15k, WK3l-120k, CN3l).
code: def _load_df(
      self, key: Union[None, EASide, Tuple[EASide, EASide]], **kwargs
  ) -> pandas.DataFrame:
      return read_zipfile_csv(
          path=self.zip_path,
          inner_path=str(
              self._relative_path(graph_pair=self.graph_pair, key=key)
          ),
          header=None,
          sep="@@@",
          engine="python",
          encoding="utf8",
          dtype=str,
          keep_default_na=False,
          **kwargs,
      )
  
imports: import itertools
  import logging
  import pathlib
  from abc import ABC
  from typing import ClassVar, Iterable, Literal, Mapping, Tuple, Union
  import click
  import pandas
  from docdata import parse_docdata
  from more_click import verbose_option
  from pystow.utils import read_zipfile_csv
  from .base import EADataset
  from ...constants import COLUMN_LABELS, PYKEEN_DATASETS_MODULE
  from ...triples import TriplesFactory
  from ...typing import EA_SIDE_LEFT, EA_SIDE_RIGHT, EA_SIDES, LABEL_HEAD, LABEL_TAIL, EASide
label_desc: Use image node_id 4 for calling the MTransEDataset obj's underlying member method code with example usage: obj._load_df(key) and returns: read_zipfile_csv